Vehicle air conditioning device using a supercritical cycle
AssigneeValeo Climatisation
InventorMohamed Ben Yahia
Life of this patent
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Abstract
An air conditioning unit including an expansion device (4) of the refrigerating fluid loop controlled to set the internal heat exchanger efficiency η, represented by the equation: η=TccTsc/TsrTsct, wherein: TccTsc and Tsr are respectively temperatures at the compressor input (1), and at the evaporator output (5) and at the fluid cooler output (2), at a reference value such that the fluid leaves the evaporator in a completely gaseous state and without overheating.
Claims16
A method for controlling a refrigerant loop in an air-conditioning unit, especially for the passenger compartment of a vehicle, said loop containing a compressor (1) suitable for receiving the refrigerant in the gaseous state and for compressing it, a refrigerant cooler (2) suitable for cooling the refrigerant compressed by the compressor, at approximately constant pressure, by transferring heat to a first medium, an expander (4) suitable for lowering the pressure of the refrigerant leaving the refrigerant cooler by taking it at least partly into the liquid state and an evaporator (5) suitable for making the refrigerant in the liquid state coming from the expander pass into the gaseous state, at approximately constant pressure, by removing heat from a second medium in order to cool the space to be air-conditioned, the refrigerant thus vaporized then being sucked up by the compressor, the loop furthermore containing an internal heat exchanger (3) allowing the refrigerant, flowing in a first path (3-1) of the internal exchanger, between the refrigerant cooler and the expander, to yield heat to the refrigerant flowing in a second path (3-2) of the internal exchanger, between the evaporator and the compressor,
- wherein in that a first condition likely to reveal the presence of refrigerant in the liquid state in said second path is monitored and the flow rate of refrigerant in the loop is reduced when said first condition is satisfied, and in which said first condition consists in that the efficiency η of the internal heat exchanger, represented by equation η = T pi - T eo T co - T eo [ 1 ]
- in which Tpi, Teo and Tco are the compressor inlet temperature, the evaporator outlet temperature and the cooler outlet temperature respectively, is less than a reference value θ0.
An air-conditioning unit, especially for the passenger compartment of a vehicle, suitable for implementing the method as claimed in one of the preceding claims, comprising a refrigerant loop, said loop containing a compressor (1) suitable for receiving the refrigerant in the gaseous state and for compressing it, a refrigerant cooler (2) suitable for cooling the refrigerant compressed by the compressor, at approximately constant pressure, by transferring heat to a first medium, an expander (4) suitable for lowering the pressure of the refrigerant leaving the refrigerant cooler by taking it at least partly into the liquid state and an evaporator (5) suitable for making the refrigerant in the liquid state coming from the expander pass into the gaseous state, at approximately constant pressure, by removing heat from a second medium in order to cool the space to be air-conditioned, the refrigerant thus vaporized then being sucked up by the compressor, the loop furthermore containing an internal heat exchanger (3) allowing the refrigerant, flowing in a first path (3-1) of the internal exchanger, between the refrigerant cooler and the expander, to yield heat to the refrigerant flowing in a second path (3-2) of the internal exchanger, between the evaporator and the compressor, monitoring means (10-15, 17) for monitoring a first condition likely to reveal the presence of refrigerant in the liquid state in said second path and, optionally, a second condition likely to reveal the existence of an overheating zone in the evaporator, and means (19, 20, 21) for controlling the flow rate of the refrigerant in the loop according to the result of this monitoring, in which the monitoring means comprise means (10-15) for evaluating the temperatures Tpi, Teo and Tco at the compressor inlet, at the evaporator outlet and at the cooler outlet respectively, means (17) for calculating from the latter the efficiency η of the internal heat exchanger on the basis of equation [1]:
- η = T pi - T eo T co - T eo [ 1 ]
- and means for comparing the efficiency η with a reference value.
Dependencies are inferred from the claim text.